Pitch Perception wtih Wind Noise

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Ron Hardin

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Aug 18, 2017, 5:02:55 PM8/18/17
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Listening to 40wpm ARRL code practice files

http://www.arrl.org/40-wpm-code-archive

with a speaker in my bicycle front basket, I
noticed a quarter-tone rise in pitch when a
headwind hit my ears.

It couldn't be doppler, because if it were I'd
soon be listening to the future and it would be a
time machine (the cycle counts have to work out).

I suspect the low frequency dominated wind noise
shifts the perceived peak in the frequency
spectrum of the tone upwards.

The tone is a sine wave, rather than a modulation.
I think with a modulation-pitch there would be no
shift.

Somebody should verify both.
--
rhha...@mindspring.com

On the internet, nobody knows you're a jerk.

Scott Dorsey

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Aug 20, 2017, 10:01:08 AM8/20/17
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Ron Hardin <rhha...@mindspring.com> wrote:
>Listening to 40wpm ARRL code practice files
>
>http://www.arrl.org/40-wpm-code-archive
>
>with a speaker in my bicycle front basket, I
>noticed a quarter-tone rise in pitch when a
>headwind hit my ears.
>
>It couldn't be doppler, because if it were I'd
>soon be listening to the future and it would be a
>time machine (the cycle counts have to work out).
>
>I suspect the low frequency dominated wind noise
>shifts the perceived peak in the frequency
>spectrum of the tone upwards.

People think they are very good at detecting pitch, but actually they are
not. There are all kinds of confounding things, which is why the piano has
so much odd stuff going on with tuning in order to make it sound like it's
in pitch.

You can think of the cochlea as being a set of filters... it's a resonant
chamber whose transverse resonance varies with length. Individual hair
cells along the cochlea get excited by sound, and due to the chamber resonance
the ones at the end get excited by higher frequencies and the ones at the
near end get excited by lower ones.

So you can think of this as a mechanical fourier transform device... it is
extracting different frequency bands individually and piping each band to
the brain as a different signal.

Change the shape of that chamber, say by pressing against the side of your
head or forcing air into the ear, and the resonances change, and the
perception of pitch changes. As you age, hair cells will die off and they
will do so selectively in different places, so not only will the hearing
thresholds change but linearity changes too. This means that intensity
begins to affect change in pitch substantially.

There is all _kinds_ of stuff that goes into pitch perception, it's a wonder
we can hear it as well as we can. With complex tones it gets even worse;
you can have situations where the perceived pitch of a complex tone depends
on the angle you're listening to it from.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Ron Hardin

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Aug 21, 2017, 3:22:26 PM8/21/17
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It's a litle more complicated because voice pitch isn't in the fourier transform.

It's a modulation frequency, not energy in the spectrum.

A sine wave however is in the spectrum, and somehow these two pitches wind up
sounding the same.

If you add random noise 1/f (wind) to an existing spectrum, the peak in the existing
spectrum shifts, so the pitch perceived should shift too, which is the effect I'm
suggesting, without any hairs dying off.

How pitch works with a voiced pitch is another matter, and I can't guess.
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